"is credible to" is correct and usable in written English.
You can use it when you want to express that something is worthy of belief or likely to be true. Example: The witness testimony is credible to the judge, so the defendant may be found guilty.
Once you catch them in one lie, nothing else they say is credible to the judge".
"But yes, I am keen that Labour presents an alternative to the government that is credible to the voters of this country.
Cynics, including many bankruptcy lawyers, will say that a plan that is credible to a banking regulator might not be credible to a bankruptcy lawyer, or more important, a bankruptcy judge.
Mr. Armey said Mr. Gillespie had argued that his party would lose because the public believed Republicans were antigovernment, "so therefore it is credible to argue Republicans shut government down".
Or as John G. Learned, a neutrino physicist at the University of Hawaii, put it in an e-mail, "An interesting result of all this fracas is that no new model I have seen (or heard of from my friends) really is credible to explain the faster-than-light neutrinos".
To use the campaign platform effectively to move a foreign policy matter, a candidate needs several elements: some personal connection with the issue; a plan that is credible to at least some serious experts and connected clearly to US national interests; and a plurality of his/her own party's intelligentsia united behind the plan.
Political attacks have to be credible to work.
Gennifer was credible to us because she looked the part".
We must be credible to develop an economy that shares wealth".
You need more sophisticated skills to assess the people behind the service and whether they're credible to deliver it".
"It's credible to think that after a normal lull there will be a resurgence," he said.
